This invention relates generally to non-lethal, non-eye-damaging security devices based on intense light and, more particularly to non-lethal, non-damaging security devices to provide low-cost, extremely effective warning, visual impairment, and disorientation through illumination by bright, visible light beams.
In recent years, the employment of non-lethal weapons has proven effective in dealing with adversaries in a variety of law enforcement, corrections, and physical security scenarios. In these areas, the goal of security personnel in most confrontations is to employ the lowest level of force necessary to control the situation. The possible levels of response fall on a force continuum ranging from a simple verbal warning through various degrees of physical interaction to the use of lethal weapons such as firearms. Within the levels of physical interaction, as the severity of response increases, the possibility of permanent injury or unintentional death also increases as does the possibility of legal or political repercussions. Also, as the level of force applied increases, adversaries will often escalate their response thereby increasing the risk of injury to the security personnel. Any means to minimize the level of interaction is therefore of great value to security personnel and their adversaries alike.
Ultra-bright light sources such as lasers offer an effective means to control escalation of confrontations between security personnel and adversaries. These light sources provide five levels of physical interaction with adversaries at the "soft" end of the force continuum: (1) language-independent, unequivocal warning; (2) psychological impact such as distraction and fear; (3) temporarily impaired vision; (4) physiological response to the light such as disorientation and nausea; and (5) reduced ability to perform hostile acts such as throwing objects, attacking, or aiming firearms. In addition, the adversaries response to the illumination can provide security personnel with threat assessment in terms of intent and resolve. Examples of such devices are described in U.S. Pat. No. 5,685,636 and U.S. patent application Ser. No. 08/967,426, now U.S. Pat. No. 6,007,218 both of which are incorporated herein by reference.
Within the various application areas, there are many scenarios where a non-lethal response with ultra-bright lights can be beneficial. These include perimeter protection for government and industrial facilities, apprehension of unarmed but violent subjects, protection from suspected snipers, protection from assailants, and crowd/mob control. Prison guards need non-lethal options in a variety of situations including cell extractions, breaking up fights, an controlling disturbances. Another important class of scenarios are those which limit the use of potentially lethal weapons because innocent people are present. These include hostage situations, protection of political figures in crowds, airport security, and crowd control.
A similar situation occurs when use of firearms or explosives in the battlefield may cause unacceptable collateral damage to equipment or facilities, such as aircraft or electronic equipment. In time-critical scenarios, such as raids on hostile facilities or criminal hideouts, where even a few seconds of distraction and visual impairment can be vital to the success of the mission, visual countermeasures can enhance the capabilities of law enforcement personnel.
Bright light sources are capable of a range of effects on human vision which depend primarily on the wavelength (measured in nanometers), beam intensity at the eye (measured in watts/square centimeter), and whether the light source is pulsed or continuous-wave. There are three types of non-damaging effects on vision: (1) glare, (2) flashblinding, and (3) physiological disorientation.
The glare effect is a reduced visibility condition due to a bright source of light in a person's field of view. It is a temporary effect that disappears as soon as the light source is extinguished, turned off, or directed away from the subject. The light source used must emit light in the visible portion of the wavelength spectrum and must be continuous or flashing to maintain the reduced-visibility glare effect. The degree of visual impairment due to glare depends on the brightness of the light source relative to ambient lighting conditions.
The flashblinding effect is a reduced visibility condition that continues after a bright source of light is switched off. It appears as a spot or afterimage in one's vision that interferes with the ability to see in any direction. The nature of this impairment makes it difficult for a person to discern objects, especially small, low-contrast objects or objects at a distance. The duration of the visual impairment can range from a few seconds to several minutes. The visual impairment depends upon the brightness of the initial light exposure and the ambient lighting conditions and the person's visual objectives. The major difference between the flashblind effect and the glare effect is that visual impairment caused by flashblind remains for a short time after the light source is extinguished, whereas visual impairment due to the glare effect does not. Some degree of flashblinding can also remain after a glare exposure, especially with laser.
Physiological disorientation occurs in response to a flashing light source. It is caused by the attempt of the eye to respond to rapid changes in light level or color. For on-and-off flashing, the pupil of the eye is continually constricting and relaxing in response to the contrasting light intensity reaching the eye. In addition, differing colors as well as differing light intensities cause the same effect.
Past concepts for the eye-safe laser security device, such as described in U.S. Pat. No. 5,685,636 and U.S. patent application Ser. No. 08/967,426 now U.S. Pat. No. 6,007,218 employ a single laser as the light source. The laser can operate at any narrow wavelength band between 400 and 700 nanometers (the entire visible light spectrum from blue to red) and provide either continuous or repetitively pulsed (on-off flashing) light. Although effective, these type of past non-lethal security devices could benefit from improvements in the areas of safety in use, overall effective, susceptibility to countermeasures, and cost.
It is therefore an object of this invention to provide a non-lethal, visual security device that is capable of low cost manufacture.
It is another object of this invention to provide a non-lethal, visual security device that is extremely effective as a visual countermeasure under a wide range of conditions.
It is still another object of this invention to provide a non-lethal, visual security device that is relatively unsusceptible to countermeasures.